Apparatus for separating used liquor from cellulosic pulp



dApril 12, 1960 J. c. F. c. RICHTER 2,932,396

APPARATUS PoR SEPARATING USED LIQUoR PROM cELLuLosIc PULP Filed Aug. 27, 1957 3 Sheets-Sheet l April 12, 1960 J. C. F. C. RIVCHTER APPARATUS FOR SEPARATING USED LIQUOR FROM CELLULOSIC PULP Filed Aug. 27, 1957 3 Sheets-Sheet 2 April 12, 1960 J. c. F. c. RICHTER 2,932,396

APPARATUS FOR SEPARATING USED LIQUOR FROM CELLULOSIC PULP 3 Sheets-Sheet 3 Filed Aug. 27, 1957 /V Vf-/VTOR Jann/v C. F C. Flc/Vrin? fig. 3

United States Patent APPARATUS Fon SEPARATING USED LIQUon PROM cELLULosrc PULP l Johan C. F. C. Richter, Karlstad, Sweden, assigner to Aktiebolaget Kamyr, Karlstad, Sweden, a company of Sweden Application August 27, 1957, Serial No. 680,483 Claims priority, application Sweden August 30, 1956 7 claims. (cl. 21o-152) The present invention -relates to an apparatus for separating used liquor from cellulosic pulp and, more particularly, to an apparatus for separating used liquor from" cellulosic pulp whenv the liquor and pulp are being fed at high pressure and high temperatures from a digester apparatus or any pressure vessel.

An object of'the present invention is lto provide an apparatus which utilizes the high pressure of the pulp in order to obtain a large pressure drop across the straining surface. i.

Another object-of the presentvinvention is to provide an apparatus which utilizes thehigh temperature of the pulp to maintain the liquor in the pulp` highly fluent so that it may be easily separated off in thev strainer.

Still another object of the present invention is to provide an apparatus whereby liquor ymay be easily and elciently separated from cellulosic pulp, the apparatus being so constructed as to utilize the high pressureand high temperature of the pulp as it is being fed from a digester or other pressure vessel.

Heretofore separation of used liquor from cellulosic pulp has been accomplishedb'y feedin-g the viscous pulp to .a cylindrical sieve. A concentric feeding screw mounted within the sieve was adapted to convey the viscous pulp axially through the sieve. Such known separators are limited in size for providing eflcient separation in that if the size of the apparatus is such that the liquor must pass through too much pulp before reaching the `straining surface, then ineilicient separation occurs. In other Words, if the distance which the liquor must pass throughtthe pulp to reach the straining Vsurface is too great the pulp will have passed'through the apparatus without theV liquor being expressed. To overcome this, the llow of pulp through the apparatus is slowed but as is obvious such apparatus becomes inefficient as the slowing down of the flow of pulp decreases the output. 'Y

The present invention eliminates the aforesaid dis- Y.

advantages in that an apparatus is provided with straining surfaces formed as rotary disc members positioned parallel to the pulp ow, the disc members being spaced transverse of the pulp flow so that the pulp flow must pass between adjacent disc members. The apparatus includes a pressure-resistant shell having an inlet adapted to be connected to adigester or any other pressure vessel and an outlet for thickened pulp. An additional outlet is provided in the shellthe second outlet being in cornmunication with the disc members, which as mentioned above, have straining'surfaces for straining olf the used liquor. A more detailed description of the Vconstruction of the pressure-resistant shell, the disc members, and the flow of pulp and liquor through the apparatus will follow later in the specification.

The above objects, as wellas additional objectsywill y 2,932,396 Patented Apr. 1,2, 11960 ice Figure 3 is a cross-sectional view of the apparatusv taken along the line III-III in Figures 1 or 2.

Figure 4 is an enlarged fragmentary sectional view of the apparatus showing in detail the construction of one of the disc members, and

Figure 5 is a sectional view taken on the line V-V of Figure 4.

Referring now to the drawings, wherein like characters or reference numerals represent like or similar parts, the preferred embodiment of the invention includes a pressure-resistant shell formed by a central cylindrical part 11 and adjoining tapered or conical end parts 13 and 15. The conical end part 13 has a center inlet 17 which is adapted to be connected to the discharge end of a cellulose digester either directly or by an interposed pressure vessel of a type known in the art. The opposite conical end part 15 of the pressure-resistant shell is attached to the center part 11 by a flange connection and is provided with an outlet 19 on its conical surface. The outlet 19 is adapted to be connected to a sluicing or throttling device of a type known in the art, by which pulp, under digester pressure, or essentially digester pressure, is continuously or in small batches delivered into a blow tank or similar apparatus having a considerably reduced pressure, the pressure sometimes even being atmospheric. A reserve outlet 21 may be provided on the surface of conical part 15 opposite the outlet 19 so that the apparatus of the present invention is capable of being used with one or more sluicing or throttling devices. In other words, by providing the additional outlet '21 the apparatus of the present invention can be quickly changed from one sluicing or throttling device to another sluicing or throttling device.

Conical end part 15 of the shell is provided with an end wall 23. A shaft 25 extends through the end wall 23 and is coaxial to the longitudinal axis of the shell. Shaft 25 is sealed against the end wall 23 by means of a stuffing box 27 and is rotatably journaled in bearings 29 and 31 carried in an extension of the conical part 15, as shown in Figure l. An agitating member 26, carried on the inner end of shaft 25, is adapted to be rotated by the shaft at a suitable speed so that thickened pulp being delivered to either of the outlets 19 or 21 is broken up and discharged through the outlets. The agitating member 26 prevents the thickened pulp from building up bridges or plugs that would block the outlets 19 or 21.

A shaft 35 extending diametrically across the cylindrical center part 11 of the shell at right angles to the longitudinal axis thereof is sealed at each end by stuing boxes 37 and is journaled in bearings 39 carried on the outside of the shell. Suitable driving means is provided for connection to one end of the shaft so that the shaft may be rotated. Shaft 35 carries a plurality of spaced sieve disc members 41, the disc members being parallel to each other and located in planes at right angles to the shaft. Only three disc members 41 are shownin the preferred arrangement of the invention but it is to be understood that any number of disc members may be utilized, the number being increased withV the increase in size and cross-section of the shell. y v

As shown in Figures 1 and 3, the disc members 41 have theirV peripheral edges positioned adjacent or close to the interior wall of the shell, the distance that each disc member is spaced from the Wall of the shell being sub'- stantially equal Consequently, the disc members 41 are of dilerent diameters depending upon their distance from the longitudinal center line of the shell. As shown in Figure 3, the disc members 41 are so arranged along the shaft 35 that the flow of pulp from the inlet 17 toward the outlets'19 or 21 is evenly distributed 'between adjacent disc members or on the outside of ther outermost disc members. By'providing disc members arranged in this manner, the pulp particles within the iiow of pulp through the apparatus are never more than half thedistance away from the planar surface of the disc members 41 and therefore, all particles of pulp are insured of passing rather close tothe sieve surfaces of the disc members before reaching the thickened pulp outlets 19 and 21. liquor inthe pulp doesnot have to liow through too much of the pulp to reach the sieve surfaces of the disc members when it is being separated from the pulp and, thus, more eiiicient separation of used liquor and pulp results.

Each of the disc members 41 comprise two substantially planar circular sieve plates 43 and 45. The plates 43 and 45 may be perforated, as shown in Figure l, by providing a plurality of narrow slits 47 therein, arranged in parallel rows close together or the plates may be provided with other shaped apertures. The sieve plates 43 and 45 are spaced apart a small distance by means of radially arranged spacer elements 49 and by a ring 51 surrounding the periphery of the disc members. The plates 43 and 45 are welded to the ring so that the ring closes the space between the plates at their periphery and, thus, prevents the escape of liquor from between the plates 43 and 45 outwardly of the disc members. A plurality of ribs 53 extending radially from and longitudinally along the drive shaft 35 define axially passages 55 between themselves. The sieve disc members 41 are centrally apertured, as shown in Figure 4 and are threaded upon the ribs 53, the edges of plates 43 and 45 adjacent the apertures being welded to spacer sleeves 56 and 57 also carried on ribs 53. As shown in Figure 3, a ring 59, provided on shaft 35 abuts and is attached to the righthand disc member 41 and thereby forms on enclosure for the passages 55 defined by the ribs 53. Ribs 53 are placed opposite the radial spacers 49 between the plates 43 and 45 when the disc members are assembled on the shaft 35. Eachpassage 55, formed longitudinally along the shaft 35, communicates with an equally located sector vof the interior of all of the disc members 41 but is closed E from adjacent sectors. Y

As shown in Figure 4, a sleeve element 61 encloses the periphery of the passages 55 defined by the ribs 53, the sleeve being positioned adjacent the disc member 41 which is opposite the disc member bearing against the ring 59. Sleeve 61, as well as the ribs 53,l extend through a stationary wall 63 in the shell, the stationary wall 63 defining a space or passageway 65 into which the passages 55 open outwardly. The shell is provided with a liquor discharge outlet 67 that is in communication with the passageway 65, the outlet 6'7 being adapted to be connected to a collecting tank or the like, in which atmospheric pressure or a low pressure, is maintained. By providing a large pressure drop between the sides of the sieve plates 43 and 45, liquor in the pulp passing between the disc members 41 is pressed through the slits 47 into the sector-shaped spaces between the sieve plates 43 and 45. The liquor flows inwardly toward the center of the disc members 41 and follows the path of the arrows shown in Figure 4 in that it is discharged to the passages 55 and flows longitudinally Valong the shaft to where it is radially discharged into the space'or passageway 65. From the passageway 65, the liquor is discharged through theoutlet 67. A plate 69 bearing against the ends of the ribs 53 provides a radial outlet or orifice for the passages 55 between the sleeve 61 and the plate 69. An arcuateshaped blind or cover fixed to the shell is adapted to cover a plurality of the orifices at the end of the passages 55. During rotation of the disc members 41, the orifices move past the cover and are successively closed whereby pres- By having disc members 41 so arranged, the

sure can build up within the disc members 41 so that the pressure between the plates 43 and 45 is substantially the same as the pressure of the pulp passing through the shell. By providing the arcuate-shaped blind or cover 71 to build up the pressure-within the disc members 41 during a portion of their'rotation, the pulp tightly pressed against the outside of the sieve plates by the differential of pressure between the outside and inside of the sieve plates, is eliminatedv when the plates have rotated to a position toward the outlets 19 or 21. Since the pressure is released, the bond between the pulp and the disc is also relieved sothat the pulp may be let loose from between adjacent disc members.

In order to guide the flow of pulp through the sieve apparatus and prevent the same from being carried around by the sieve discs in a complete circle, the shell has a partition which allows free passage of the pulp merely on one side of the shaft of the sieve discs. In the embodiment shown, the partition is formed as a plate 73 attached to the wall and extending inwardly towards the shaft 35. The plate 73 has a half-circular edgev fitting the inside of the shell along the upper half of its periphery and is attached to knobs 75 thereon. The inwardly and downwardly directed free edge of the'plate is slit like a cam and forms resilient tongues 77, 79, 81, 83 extending in between and kalong the sides of the sieve discs and bearing with their ends against the rotary sleeves 61, 56, 57 and the'ring'59, respectively, and preferably also against the sleeve-like ends 85, 87 of the stufing boxes 37. The line of contact is located on the outlet side of the shaft 35 and the tongues extend approximately in the direction of a tangent to the shaft of the rotary disc set. The plate 73 is slightly bent and forms part of a cylinder, the generatrices of which are parallel to the shaft 35, the concave side of the plate facing the shaft 35 or the inlet 17. By designing the partition plate 73 in this manner it serves as a deiiector or scraper for removing pulp from the spaces between the sieve discs and for conveying it towards the outlet. When the sieve disc members 41 turn in the'direction indicated by the arrow 89, of Figure l, pulp sticking to the disc members will meet the plate 73 in an acute angle and be forced to slide in a spiral path toward the periphery of the sieve disc members. Removal of the pulp is also facilitated, as heretofore mentioned, by the sectors of the interior space of the sieve disc members located opposite the plate 73 being shut off from communication with the outlet 67, so that the pressure of the pulp against the sieve disc members is relieved at these places.

The above-described design of the straining device constitutes merely an example of the practical application of the invention and it is obvious that the design can be modified in several respects without departing from the spirit of the invention. For instance, the device may be modified with respect to the shape of the shell and the location of the inlet, the inlet 17' for instance being located on the upper side of the shell and the inlet end of the shell being half-spherical in shape. The sieve disc members may be built in a different manner and the `liquor outlet passages may be arranged within the shaft 35 and may lack any binding means 71.

The terminology used in this specification is for the purpose of description and not limitation, the scope of the invention being defined in the claims.

-I claim:

1. In an apparatus of the type adapted for use in separating used liquor from cellulosic pulp, the liquor and pulp being Ifed under pressure from a digester or the like: a shell having an inlet adapted to be connected to the digester for receiving ow of liquor and pulp, a first Voutlet for discharge of thickened pulp and a second outlet for discharge of separated liquor, said shell being circular in cross-section taken in a plane transverse to the liow of liquor and pulp; a plurality of spaced parallel substantially planar members mounted within saidV Y shell normal to its plane of circular cross-section, said members having varying diameters so that their peripheral edges are equallydistanced from the wall of said shell, each of said members being provided with apertures on each of its planar surfaces, and passages therein communicating with said apertures;V and means providing communication between the passages in said members and said second outlet in said shell for discharge of liquor expressed through the apertures in said members.

2. An apparatus of the character described in claim 1, including means to vary pressure within said planar members.

3. In an apparatus of the type adapted for use in separating used liquor from cellulosic pulp, the liquor and pulp being fed under pressure from a digester or the like:

a shell having an inlet adapted to be connected to the digester for receiving ilow of liquor and pulp, a first outlet for discharge of thickened pulp, and a second outlet for discharge of separated liquor, said shell being approximately circular in cross-section taken on a plane normal `to, the owv of liquor and pulp; a rotatable shaft extending through said shell in its plane of circular crosssection, a plurality of spaced disc members carried by said shaft for rotation therewith, said disc members having varying diameters so that their peripheral edges are equally distanced fromrthe wall of said shell, each of said disc members comprising closely spaced sieve plates closed at the periphery, said rotary shaft being provided with a passage in communication with the spaces between the plates of each of said disc members andin communication with said second outlet in said shell for carrying off liquor expressed through the plates of said disc members.

4. An apparatus of the character described in claim 3 including means to vary pressure across said sieve plates during rotation of said disc members. Y

5. An apparatus of the character described in claim 3, including a plate extending from the wall of said shell and provided with tongue-like portions extending between each of said disc members toward said shaft.

6. An apparatus of the character described in claim 3, including an agitator rotatably mounted on an axis transverse of the axis of said disc members, said agitator being positioned on the outlet side of said disc members and arranged torcause the thickened pulp passing from` between said disc members to break up and discharge through said irst outlet.

7. An apparatus of the character described in claim 5, including means to vary pressure across said disc members so that pulp removed by said tongue-like portions is facilitated.

France Aug. 13, 1912 (Addition to No. 427,901) 

